Car stops without warning

Intermittent faults are the most difficult ones to trace, if they don't happen when the mechanic or auto elec is present he can only guess as what might be wrong. That's what seems to have happened with your car, as they've replaced the most obvious things that could be the cause of the problem. My first thought would be a faulty sensor, but as you have replaced them, I would move on to the connections and make sure there are no problems there.